浅尾水深水平底板上表面射流水力特性的数值模拟研究

Numerical simulation of hydraulic characteristics of surface jet on horizontal base plate with shallow depth

采用VOF(volume of fluid)方法追踪自由液面,辅以Realizable(可实现化)湍流模型封闭两相流时均方程,对浅尾水深水平底板上的表面射流水力特性进行了数值模拟。微分方程的离散采用有限体积法,速度与压力耦合求解使用了压力隐式算子分裂PISO(Pressure-Implicit with Splitting of Operators)算法。研究并分析了入射速度、尾水深和进口宽度等对流场流线分布、速度场及横断面最大流速沿程衰减规律等水力特性的影响。研究发现:流场内存在一个大的漩涡,入射流速越大,漩涡长度越长;横断面上水平流速和纵向流速在漩涡区和明渠流区分布规律不同;横断面最大流速沿程衰减主要受进口流速大小的影响。

The VOF（ volume of fluid） method was applied to track free water surface,and the Realizable turbulent model was used to close the two-phase flow time-averaged equation to numerically simulate the hydraulic characteristics of surface jet on horizontal base plate with shallow depth. The finite volume method was used to discretize the differential equation,and the coupling velocity and pressure equations were solved with the pressure-implicit method of splitting operators（ PISO） algorithm. The influence of inlet velocity,depth of shallow tail and width of nozzle on the characteristics of streamline distribution,velocity field and the variation of the maximum velocity on a cross-section along the flowing direction was studied and analyzed. The result showed that a big vortex exists in the flow field,and the greater the inlet flow velocity,the longer the length of vortex. The distribution laws of horizontal velocity and longitudinal velocity of a cross section are different in the backflow region and open channel flow region. The gradient decaying of the maximum velocity on cross-section was mainly affected by the inlet velocity.